Materials used for components subjected to a bending stress e.g. gear wheels are subjected to local stress concentrations, and it is preferred that these materials have superior properties at the local stress maximum regions.
An example of such a material is disclosed in EP 552 272 which concerns sintered powder metal blanks having densified surface regions. According to this publication the densified regions are obtained by rolling.
It is also known that the surfaces of sintered powder metallurgical parts can be densified by using shot peening. The purpose of shot peening the surfaces of these sintered parts is to induce compressive stress in the surfaces, which in turn results in sintered parts having improved fatigue strength, surface hardness etc.